On lightly floured surface, with hands, shape each half into 10-inch-long log. Using hands or two clean rulers on sides, press each log into 10-inch-long squared-off log. Wrap each in plastic wrap and freeze until firm enough to slice, 2 hours or refrigerate overnight. (Logs can be frozen up to 1 month.)

Preheat oven to 350 degrees F. On 1 sheet of waxed paper, place green sugar. Unwrap 1 log and press sides in sugar to coat. Cut log into 1/4-inch-thick slices. Place slices, 1 inch apart, on ungreased large cookie sheet. Bake cookies 14 to 16 minutes or until golden. Transfer cookies to wire rack to cool. Repeat with red sugar and second log.

Store cookies in tightly sealed container at room temperature up to 1 week or in freezer up to 3 months.